The MEMS technology of forming micro-mechanical parts or mechanical systems by using fine fabrication technique which has realized high performance and high degree of integration in semiconductor integrated circuits has attracted attention. While mechanical sensors for measuring physical quantity such as pressure and acceleration or mechanical actuators such as micro switches or oscillators by using the MEMS technique have already been put to practical use, it has further been discussed around the presentation of subjects to be solved and specific measures for proceeding research and development as the technique of adding values to products in various fields.
The MEMS technique is generally classified into a bulk MEMS technique of fabricating a silicon substrate per se and a surface MEMS technique of forming products by repeating thin film deposition and patterning above the surface of silicon substrates. The surface MEMS technique is more similar to the production process of semiconductor integrated circuits and applied, for example, to ultrasonic transducers (refer, for example, to the specification of U.S. Pat. No. 6,426,582B1).